Diethyl amlodipine besylate salt

Diethyl amlodipine besylate salt is a synthetic byproduct arising from the alkylation step in amlodipine synthesis, featuring a diethyl-substituted 1,4-dihydropyridine core conjugated to a benzenesulfonate ester. Its structure retains the calcium-channel blocker scaffold of amlodipine but incorporates an ethyl group at the 3-position of the dihydropyridine ring, displacing a hydrogen atom. This impurity forms via premature termination of the amidation reaction during API synthesis. The compound serves as a critical HPLC reference standard for quantifying process-related impurities in amlodipine formulations.